How do you convert a string from toLowerCase to toUpperCase and toLowerCase to toUpperCase?

I have no clue how to figure this problem out.

public class Strings
{
    // instance variables - replace the example below with your own
   

    /**
     * Constructor for objects of class Strings
     */
    public Strings()
    {
       
    }

    /**
     * Write a method that takes a string and returns a new string that changes the case of every character in
     * the original string changed from lowercase to uppercase and vice versa. Note that upper/lower case doesn't
     * apply to some characters such as numbers or punctuation.
     * @param  y   a sample parameter for a method
     * @return     the sum of x and y
     */
    public String changeCase(String s)
    {
        if(s.toLowerCase())
        {
            return s.toUpperCase();
            else if(s.toUpperCase())
            return s.toLowerCase();
        }
       
    }
}
ryanbecker24Asked:
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for_yanConnect With a Mentor Commented:

well in any case I'm not writng anything for you but if you go to internet, you can find such things, like in this link:
http://stackoverflow.com/questions/1729778/how-can-i-invert-the-case-of-a-string-in-java
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for_yanCommented:
Is this an academic assignemnt?
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ryanbecker24Author Commented:
No, I have always wondered how to figure this out. I just decided to make an empty class just for fun. I know how to go from a regular string to lower case and reg string to upper case but I don't know how to go back and forth.
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ryanbecker24Author Commented:
Thank you, I have been looking all over the internet for this. I copied and pasted it. It compiles but it doesn't show the case switch from uppercase to lowercase. It shows lowercase to uppercase. I am using BlueJ. Do you know why this is?
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for_yanCommented:
Post your exact code, I'll look at it.
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ryanbecker24Author Commented:
public String caseChange(String s)
   {     char[] characters = s.toCharArray();    
       for (int index = 0; index < characters.length; index++)    
       {         char c = characters[index];        
           if (Character.isUpperCase(c))        
           {            
               characters[index] = Character.toLowerCase(c);        
            }         else if (Character.isLowerCase(c))        
            {             characters[index] = Character.toUpperCase(c);        
            }    
        }     return new String(characters);
    }
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for_yanCommented:
Just pasted your code - seesm to be working fine for me - look at the output below

 public static String caseChange(String s)
   {     char[] characters = s.toCharArray();
       for (int index = 0; index < characters.length; index++)
       {         char c = characters[index];
           if (Character.isUpperCase(c))
           {
               characters[index] = Character.toLowerCase(c);
            }         else if (Character.isLowerCase(c))
            {             characters[index] = Character.toUpperCase(c);
            }
        }     return new String(characters);
    }


    

    public static void main(String[] args) {


      System.out.println(caseChange("ASADhjRTklui54"));


}

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output:

asadHJrtKLUI54

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ryanbecker24Author Commented:
It works now. I just closed BlueJ and opened it again. Thanks.
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for_yanCommented:
You are welcome.

Better go away from BlueJ - that's not the most popular stuff - and perhpas has some quirks.
Rather use some normal IDE, like Eclipse.
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